Use of partially fluotinated polymers in applications requiring transparency in the ultraviolet and vacuum ultraviolet

ABSTRACT

Disclosed are partially fluorinated that are substantially transparent to ultraviolet radiation at wavelengths from approximately 150 nanometer to 260 nanometers.

FIELD OF THE INVENTION

[0001] The present invention provides methods and associated apparatusfor transmission of light in the range of 150 to 260 nanometers (nm),especially at 157 nm, 193 nm, and 248 nm, utilizing partiallyfluorinated polymers exhibiting high transparency.

TECHNICAL BACKGROUND OF THE INVENTION

[0002] The semiconductor industry is the foundation of the trilliondollar electronics industry. The semiconductor industry continues tomeet the demands of Moore's law, whereby integrated circuit densitydoubles every 18 months, in large part because of continuous improvementof optical lithography's ability to print smaller features on silicon.This in turn depends in part upon identifying materials which exhibitsufficient transparency for practical use at ever-shorter wavelengths.For example, in photolithography, a circuit pattern is represented in aphotomask, and an optical stepper is used to project the mask patternonto a photoresist layer on a silicon wafer. Currently commercial scalephotolithography is done at 248 nm. Lithography at 193 nm light is justentering early production. Current developmental efforts are directed tophotolithography at 157 nm. A general discussion of photolithographicmethods in electronics and related applications may be found in L. F.Thompson, C. G. Willson, and M. J. Bowden, editors, Introduction toMicrolithography, Second Edition, American Chemical Society, Washington,D.C. 1994

[0003] Polymers play a critical role in lithography in multiple areas:one is the polymer pellicle which is placed over the mask pattern tokeep any particulate contaminants out of the photomask object plane,thereby ensuring that the lithographic imaging will be defect free. Thepellicle is a free standing polymer membrane, typically 0.8 micrometersin thickness, which is mounted on a typically 5 inch square frame. Thepellicle film must have high transparency or transmission of light atthe lithographic wavelength for efficient image formation and mustneither darken nor burst with prolonged illumination in the opticalstepper. Typical commercial processes utilize pellicles with >99%transmission through exploitation of polymers with very low opticalabsorption combined with thin film interference effects. The electronicsindustry requires greater than 98% transparency over an exposurelifetime of 75 million laser pulses of 0.1 mJ/cm², or a radiation doseof 7.5 kJ/cm².

[0004] A pellicle transmission of 98% corresponds to an absorbance A ofapproximately 0.01 per micrometer of film thickness. The absorbance isdefined in Equation 1, where the Absorbance A in units of inversemicrometers (μm⁻¹) is defined as the base 10 logarithm of the ratio ofthe substrate transmission, T_(substrate), divided by the transmissionof the sample, consisting of the polymer film sample on the substrate,T_(sample), divided by the polymer film thickness, t, in micrometers.$\begin{matrix}{{A_{film}\left( {µm}^{- 1} \right)} = {{A/{um}} = {\frac{{Log}_{10}\left\lfloor {T_{substrate}/T_{sample}} \right\rfloor}{t_{film}}.}}} & {{Equation}\quad 1}\end{matrix}$

[0005] Certain perfluoropolymers have been identified in the art asuseful for optical applications such as light guides, anti-reflectivecoatings and layers, pellicles, and glues mostly at wavelengths above200 nm

[0006] WO 9836324, Aug. 20, 1998, Mitsui Chemical Inc., discloses theuse of perfluorinated polymers, optionally in combination with siliconepolymers having siloxane backbones, as pellicle membranes having anabsorbance/micrometer of 0.1 to 1.0 at UV wavelengths from 140 to 200nm.

[0007] WO 9822851, May 28,1998, Mitsui Chemicals, Inc., claims the useat 248 nm of low molecular weight photodegradation-resistant, polymericadhesives consisting largely of −(CF2−CXR) copolymers in which X ishalogen and R is −Cl or −CF3. Higher molecular weight polymers such aspoly(perfluorobutenyl viny ether),poly[(tetrafluoroethylene/perfluoro-(2,2-dimethyl -1,3-dioxole)],poly(tetrafluoroethylene/hexafluoropropylene/vinylidene fluoride),poly(hexafluoropropylene/vinylidene fluoride), or poly(chlorotolylfluoroethylene/vinylidene fluoride) are disclosed as minor components toimprove creep resistance. Only poly(chlorotrifluoroethylene) wasexemplified.

[0008] Japanese Patent 07295207, Nov. 10, 1995, Shinetsu Chem. Ind Co,claims double layer pellicles combining Cytop CTXS(poly(CF2=CFOCF2CF2CF=CF2)) with Teflon® AF 1600 for greater strength.

[0009] U.S. Pat. No. 5286567, Feb. 15,1994, Shin-Etsu Chemical Co.,Ltd., claims the use of copolymers of tetrafluoroethylene and fivemembered cyclic perfluoroether monomers as pellicles once they have beenmade hydrophilic, and therefore antistatic, by plasma treatment.

[0010] European Patent 416528, Mar. 13, 1991, DuPont, claims amorphousfluoropolymers having a refractive index of 1.24-1.41 as pellicles atwavelengths of 190-820 nm. Copolymers of perfluoro(2,2-dimethyl-1,3-dioxole) with tetrafluoroethylene, chlorotrifluoroethylene,vinylidene fluoride, hexafluoropropylene, trifluoroethylene, vinylfluoride, (perfluoroalkyl)ethylenes, and perfluoro(alkyl vinyl ethers)are cited.

[0011] Japanese Patent 01241557, Bando Chemical Industries, Ltd., Sep.26, 1989, claims pellicles usable at 280-360 nm using (co)polymers ofvinylidene fluoride (VF2), tetrafluoroethylene/hexafluoropropylene(TFE/HFP), ethylene/tetrafluoroethylene (E/TFE), TFE/CF2=CFORf,TFE/HFP/CF2=CFORf, chlorotrifluoroethylene (CTFE), E/CTFE, CTFE/VF2 andvinyl fluoride (VF).

[0012] Japanese Patent 59048766, Mar. 21, 1984, Mitsui Toatsu Chemicals,Inc., claims the use of a stretched film of poly(vinylidene fluoride) ashaving good transparency from 200 to 400 nm.

[0013] French et al, WO0137044, discloses vacuum ultraviolet (VUV)transparent materials exhibiting an absorbance/micron (A/micrometer)≦1at wavelengths from 140-186 nm comprising amorphous vinyl homopolymersof perfluoro-2,2-dimethyl-1,3-dioxole or CX2=CY2, where X is -F or -CF3and Y is H, or amorphous vinyl copolymers of perfluoro-2,2-dimethyl-1,3-dioxole and CX2=CY2.

[0014] French et al, WO0137043 discloses ultraviolet transparentmaterials exhibiting an absorbance/micron (A/micrometer)≦1 atwavelengths from 187-260 nm comprising amorphous vinyl copolymers ofCX2=CY2, wherein X is -F or -CF3 and Y is H and 0 to 25 mole % of one ormore monomers CRaRb=CRcRd where the CRaRb=CRcRd enters the copolymer inapproximately random fashion, or 40 to 60 mole % of one or more monomersCRaRb=CRcRd in the case where the CRaRb=CRcRd enters the copolymer inapproximately alternating fashion where each of Ra, Rb, and Rc isselected independently from H or F and where Rd is selected from thegroup consisting of -F, -CF3, -ORf where Rf is CnF2n+1 with n=1 to 3,-OH (when Rc=H), and Cl (when Ra, Rb, and Rc=F).

[0015] Japanese Patent Application Kokai Number P2000-305255A Shin-EtsuChemical Company discloses copolymers containing >70%perfluorodimethyldioxole and 0-30 mole % tetrafluoroethylene,trifluoroethylene, difluoroethylene, vinylidene fluoride, andhexafluoropropylene for use as pellicles at 158 nm.

[0016] Japanese Patent publication P2000-338650AShin-Etsu ChemicalCompany discloses copolymers containing >20% ofperfluoralkoxysubstituted dioxoles such as2,2,4-trifluoro-5-trifluoromethoxy -1,3-dioxole with F-containingradically polymerizing monomers such as tetrafluoroethylene,trifluoroethylene, difluoroethylene, vinylidene fluoride, andhexafluoropropylene for use as pellicles at 157 nm.

[0017] US Patent publication 20010024701 from Asahi Glass Companydiscloses fluorine containing polymers having a polymer chain consistingof carbon atoms wherein some chain carbons are substituted with fluorineand unspecified fluorine-containing groups. Encompassed in thedisclosure are numerous polymers which are unsuitable in practice foruse in applications at 157 nm because they are strongly absorbing orhighly crystalline with concomitant high light scattering. Pellicles areinoperable without reasonably high transparency and yet the claims aswritten could include 100% opaque materials and fails to teach anymethod by which highly useful and completely useless polymer candidatesfor such applications can be distinguished from one another.

[0018] Many of the fluoropolymers cited in the references above arenoticeably hazy to the eye because of crystallinity and are thereforeunsuitable for applications requireing high light transmission and theprojection of precision circuit patterns. Poly(vinylidene fluoride),poly(chlorotrifluoroethylene), poly(tetrafluoroethylene/ethylene),commercially available poly(tetrafluoroethylene/hexafluoropropylene)compositions, and poly(ethylene/chlorotrifluoroethylene) are all suchcrystalline, optically hazy materials. More recent references have thusbeen directed at amorphous perfluoropolymers such as Cytop® and Teflon®AF because they combine outstanding optical clarity down to at least 193nm, solubility, and a complete lack of crystallinity.

[0019] Absorption maxima for selected hydrocarbon and fluorocarboncompounds are shown in Table 1. For hydroorocarbons H(CH₂)_(n)H the datafor n=1−8 is cited in B.A. Lombos et al Chem, Phys. Lett., 1967, 42. Forfluorocarbons F(CF2)nF the n=3−6 data is cited in G. Belanger et. al.,Chem. Phys. Letters, 3, 649(1969) while the datum for n=172 is cited inK. Seki et al, Phys. Scripta, 41, 167(1990). TABLE 1 Comparison of UVAbsorption Maxima for Hydrocarbons and Fluorocarbons WAVELENGTH OFABSORPTION MAXIMUM C_(n)H_(2n+2) C_(n)F_(2n+2) n = 1 143 nm & 128 nm n =2 158 nm & 132 nm n = 3 159 nm & 140 nm 119 nm n = 4 160 nm & 141 nm 126nm n = 5 161 nm & 142 nm 135 nm n = 6 162 nm & 143 nm 142 nm n = 7 163nm & 143 nm n = 8 163 nm & 142 nm n = 172 161 nm

[0020] As can be seen from the table, UV absorption maxima move tolonger wavelengths as chain length increases for both hydrocarbons andfluorocarbons. Perfluorocarbon chains (CF₂)_(n) absorb at 157 nmsomewhere between n=6 (142 nm) and n=172 (161 nm) while hydrocarbonchains (CH₂)_(n) absorb at 157 nm perhaps as early as n=2. But, as longas chain lengths offering acceptable transparency are limited to (CH₂)₁or (CF₂)₆, perfectly transparent polymers at 157 nm and somewhat longerwavelengths would seem precluded according to the known art. Consistentwith this, V.N. Vasilets, et al., J. Poly. Sci, Part A, Poly. Chem., 36,2215(1998) for example report that various compositions ofpoly(tetrafluoroethylene/hexafluoropropylene) show strong absorption andphotochemical degradation at 147 nm. Similarly the inventors hereof havefound that 1:1 poly(hexafluoropropylene:tetrafluoroethylene) is highlyabsorbing at 157 nm

[0021] The absorbance per micron of a polymer will determine the averagetransmission of an unsupported pellicle film made from that polymer. Forany particular polymer, the pellicle transmission can be increased,through the use of a thinner pellicle film thickness. This approach toincreasing the pellicle transmission has a limited range of utility,since the pellicle film must have sufficient mechanical strength andintegrity. These mechanical requirements suggest the use of polymer withrelatively high glass transition temperature Tg and polymer filmthicknesses of 0.6 microns or greater.

SUMMARY OF THE INVENTION

[0022] This invention provides a method comprising causing a source toemit electromagnetic radiation in the wavelength range from 150nanometers to 260 nanometers; disposing a target surface in the path ofat least a portion of said electromagnetic radiation in such a mannerthat at least a portion of said target surface will be therebyilluminated; and interposing in the path of at least a portion of saidelectromagnetic radiation between said target surface and said source ashaped article comprising a fluoropolymer exhibiting anabsorbance/micrometer ≦1 at wavelengths in the range of 150 to 260 nmand a heat of fusion of <1 J/g said fluoropolymer being a homopolymerselected from group A or copolymers from groups B, C, and D wherein

[0023] group A consists of the homopolymer of CH₂=CFCF₃

[0024] group B consists of copolymers comprising >25 mole % of monomerunits derived from CF₂=CHOR_(f) in combination with monomer unitsderived from vinylidene fluoride wherein R_(f) is a linear or branchedC1 to C6 fluoroalkyl radical having the formula C_(n)F_(2n−y+1) H_(y)wherein the number of hydrogens is less than or equal to the number offluorines, no more than two adjacent carbons atoms are bonded tohydrogens, and ether oxygen can replace one or more of the carbonsproviding at least one of the carbons adjacent to any ether oxygen isperfluorinated;

[0025] group C consists of copolymers comprising >10 mole % of monomerunits derived from CH₂=CFCF₃, CF₂=CHOR_(f), or a mixture thereof incombination with monomer unit derived from 1,3 perfluorodioxoles whereinR_(f) is a linear or branched C1 to C6 fluoroalkyl radical having theformula C_(n)F_(2n−y+1) H_(y) wherein the number of hydrogens is lessthan or equal to the number of fluorines, no more than two adjacentcarbon atoms are bonded to hydrogens, and ether oxygen can replace oneor more of the carbons providing at least one of the carbons adjacent toany oxygen is perfluorinated, and wherein said 1,3-perfluorodioxole hasthe structure

[0026] wherein R_(a) and R_(b) are independently F or linear−C_(n)F_(2n+1) , optionally substituted by ether oxygen, for which n=1to 5.

[0027] group D consists of copolymers comprising 40 to 60 mole % ofmonomer units derived from a monomer represented by the formula

[0028] in combination with monomer units derived from vinylidenefluoride and or vinyl fluoride wherein G and Q are independently F (butnot both F), H, R_(f), or -OR_(f) whereinR_(f =l is a linear or branched C)1 to C5 fluoroalkyl radical having theformula C_(n)F_(2n−y+1)H_(y) wherein the number of hydrogens is lessthan or equal to the number of fluorines, no more than two adjacentcarbons atoms are bonded to hydrogens, and ether oxygen can replace oneor more of the carbons providing that at least one of the carbonsadjacent to any ether oxygen is perfluorinated.

[0029] Further provided in the present invention is an apparatuscomprising an activateable source of electromagnetic radiation in thewavelength range of 150-260 nanometers; and a shaped article comprisinga fluoropolymer exhibiting an absorbance/micron ≦1 at wavelengths from150 to 260 nm and a heat of fusion of <1 J/g said fluoropolymer being ahomopolymer selected from group A or copolymers from groups B, C, and Dwherein

[0030] group A consists of the homopolymer of CH₂=CFCF₃

[0031] group B consists of copolymers comprising >25 mole % of monomerunits derived from CF₂=CHOR_(f) in combination with monomer unitsderived from vinylidene fluoride wherein R_(f) is a linear or branchedC1 to C6 fluoroalkyl radical having the formula C_(n)F_(2n−y+1)H_(y)wherein the number of hydrogens is less than or equal to the number offluorines, no more than two adjacent carbons atoms are bonded tohydrogens, and ether oxygen can replace one or more of the carbonsproviding at least one of the carbons adjacent to any ether oxygen isperfluorinated;

[0032] group C consists of copolymers comprising >10 mole % of monomerunits derived from CH₂=CFCF₃, CF₂=CHOR_(f), or a mixture thereof incombination with monomer unit derived from 1,3 perfluorodioxoles whereinR_(f) is a linear or branched C1 to C6 fluoroalkyl radical having theformula C_(n)F_(2n−y+1) H_(y) wherein the number of hydrogens is lessthan or equal to the number of fluorines, no more than two adjacentcarbons atoms are bonded to hydrogens, and ether oxygen can replace oneor more of the carbons providing at least one of the carbons adjacent toany oxygen is perfluorinated, and wherein said1,3-perfluorodioxole hasthe structure

[0033] wherein R_(a) and R_(b) are independently F or linear−CnF_(2n+1,) optionally substituted with ether oxygen, for which n=1 to5.

[0034] group D consists of copolymers comprising 40 to 60 mole % ofmonomer units derived from a monomer represented by the formula

[0035] in combination with monomer units derived from vinylidenefluoride and or vinyl fluoride wherein G and Q are independently F (butnot both F), H, R_(f), or -OR_(f) wherein R_(f) is a linear or branchedC1 to C5 fluoroalkyl radical having the formula C_(n)F_(2n−y+1) H_(y)wherein the number of hydrogens is less than or equal to the number offluorines, no more than two adjacent carbons atoms are bonded tohydrogens, and ether oxygen can replace one or more of the carbonsproviding that at least one of the carbons adjacent to any ether oxygenis perfluorinated;

[0036] said shaped article being disposed to lie within the optical pathof light emitted from said source when said source is activated.

[0037] This invention further provides pellicles, anti-reflectivecoatings, optically clear glues, light guides and resists comprising theUV transparent material described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038]FIG. 1 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofExample 1 (Poly[(CH₂=C(CF₃)CF₂OCH(CF₃)₂/CH₂=CF₂).

[0039]FIG. 2 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers for the polymer of Example 1.

[0040]FIG. 3 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofExample 2 (Poly[(CH₂=C(CF₃)CF₂OCF(CF₃)₂/CH₂=CF₂).

[0041]FIG. 4 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers for the polymer of Example 2(Poly[(CH₂=C(CF₃)CF₂OCF(CF₃)₂/CH₂=CF₂).

[0042]FIG. 5 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofexample 3 (Poly(CF₂=CHOCF₂CF₂H/CH₂=CF₂).

[0043]FIG. 6 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers. for the polymer of Example 3(Poly(CF₂=CHOCF₂CF₂H/CH₂=CF₂)).

[0044]FIG. 7 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofExample 4 (Poly(CF₂=CHOCF₂CF₂H/PDD)).

[0045]FIG. 8 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers. for the polymer of Example 4(Poly(CF₂=CHOCF₂CF₂H/PDD)).

[0046]FIG. 9 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofExample 5 (Poly(CF₂=CHOCF₂CF_(3/)CH₂=CF₂)).

[0047]FIG. 10 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers for the polymer of Example 5(Poly(CF₂=CHOCF₂CF₃/CH₂=CF₂))

[0048]FIG. 11 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofExample 6 (Poly(CF₂=CHOCF₂CF₂CF₂CF₃/PDD)).

[0049]FIG. 12 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers for the polymer of Example 6(Poly(CF₂=CHOCF₂CF₂CF₂CF₃/PDD)).

[0050]FIG. 13 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofExample 7 (Poly(CH₂=CFCF₃)).

[0051]FIG. 14 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers.for the polymer of Example 7(Poly(CH₂=CFCF₃)).

[0052]FIG. 15 describes the absorbance in units of inverse micrometersversus wavelength lambda (λ) in units of nanometers for the polymer ofExample 8 (Poly(CH2=CFCF3/PDD)).

[0053]FIG. 16 describes the index of refraction (n) versus wavelengthlambda (λ) in units of nanometers.for the polymer of Example 8(Poly(CH2=CFCF3/PDD)).

DETAILED DESCRIPTION OF THE INVENTION

[0054] The method of the present invention has several embodiments, allrelated to the use of electromagnetic radiation in the range of 150 nmto 260 nm for illuminating a surface. In a preferred embodiment of themethod of the invention, the method is applied in the area ofphotolithographic processes for the fabrication of circuit elements inelectronics as described hereinabove and in the references cited. Inother embodiments, the method may be applied to vacuum ultravioletspectroscopy, or in microscopy. Since the novelty of the method lies inthe use of polymeric materials heretofore unknown to be useful fortransmitting electromagnetic radiation in the wavelength region from 150nm-260 nm in there is no limitation on the number of potentialembodiments just so long as the elements of the present method areapplied.

[0055] In the method of the invention, a source of electromagneticradiation such as a lamp (such as a mercury or mercury-xenon lamp, adeuterium lamp or other gas discharge lamp of either the sealed orflowing gas type), an excimer lamp such as produces 172 nm radiation orother lamps) , a laser (such as the excimer gas discharge lasers whichproduce 248 nm electromagnetic radiation from KrF gas, 193nm radiationfrom ArF gas or 157 nm from F2 gas, or frequency up converterd as by nonlinear optical processes of laser whose emission in in the ultraviolet,visible or infrared), ablack body light source at a temperature of atleast 2000 degrees kelvin. An example of such a black body light sourcebeing a laser plasma light source where by a high powered laser isfocused to a small size onto a metal, ceramic or gas target, and aplasma is formed as for example in the samarium laser plasma lightsource whereby a black body temperature on the order of 250,000 degreesKelvin is achieved, and black body radiation from the infrared to thex-ray region can be produced, LPLS light sources which emits radiationin the wavelength range from 150 nm to 260 nm are discussed in greaterdetail in R. H. French, “Laser-Plasma Sourced, Temperature Dependent VUVSpectrophotometer Using Dispersive Analysis”, Physica Scripta, 41, 4,404-8, (1990)). In a preferred embodiment, the source is an excimer gasdischarge laser emitting at 157 nm, 193 nm, or 248 nm, most preferably,157 nm.

[0056] At least a portion of the light emitted from the source isdirected to a target surface at least a portion of which will beilluminated by the incident light. In a preferred embodiment, the targetsurface is to be a photopolymer surface which undergoes light-inducedchemical reaction in response the incidence of the radiation. Clarianthas just introduced a 157 nm fluoropolymer resist under the name AZ EXPFX 1000P which is likely a hydrofluorocarbon polymer incorporating ringstructures for etch stability and protected fluoroalcohol groups foraqueous base solubility.

[0057] In the process for manufacturing semiconductor devices, very finefeatures are etched onto a substrate, typically a silicon wafer. Thefeatures are formed on the substrate by electromagnetic radiation whichis impinged, imagewise, on a photoresist composition applied to thesilicon wafer. Areas of the photoresist composition which are exposed tothe electromagnetic radiation change chemically and/or physically toform a latent image which can be processed into an image forsemiconductor device fabrication. Positive working photoresistcompositions generally are utilized for semiconductor devicemanufacture.

[0058] The photoresist composition typically is applied to the siliconwafer by spin coating. The silicon wafer may have various other layersapplied to it in additional processing steps. Examples of suchadditional layers such as are known in the art include but are notlimited toa hard mask layer, typically of silicon dioxide or siliconnitride, and an antireflective layer. Typically the thickness of theresist layer is sufficient to resist the dry chemical etch processesused in transferring a pattern to the silicon wafer.

[0059] A photoresist is typically comprised of a polymer and at leastone photoactive component. The photoresists can either bepositive-working or negative-working. Positive-working photoresists arepreferred. These photoresists can optionally comprise dissolutioninhibitors and/or other additional components such as are commonlyemployed in the art. Examples of additional components include but arenot limited to, resolution enhancers, adhesion promoters, residuereducers, coating aids, plasticizers, and T_(g) (glass transitiontemperature) modifiers Various polymer products for photoresistcompositions have been described in Introduction to Microlithography,Second Edition by L. F. Thompson, C. G. Willson, and M. J. Bowden,American Chemical Society, Washington, DC, 1994.

[0060] The photoresist composition generally comprises a film formingpolymer which may be photoactive and a photosensitive composition thatcontains one or more photoactive components. Upon exposure toelectromagnetic radiation (e.g., UV light), the photoactive componentacts to change the rheological state, solubility, surfacecharacteristics, refractive index, color, optical characteristics orother such physical or chemical characteristics of the photoresistcomposition.

[0061] Shorter wavelengths correspond to higher resolution.

[0062] Imagewise Exposure

[0063] The photoresist compositions suitable for use in the process ofthe instant invention are sensitive in the ultraviolet region of theelectromagnetic spectrum and especially to those wavelengths ≦365 nm.Imagewise exposure of the resist compositions of this invention can bedone at many different UV wavelengths including, but not limited to, 365nm, 248 nm, 193 nm, 157 nm, and lower wavelengths. Imagewise exposure ispreferably done with ultraviolet light of 248 nm, 193 nm, 157 nm, orlower wavelengths, more preferably it is done with ultraviolet light of193 nm, 157 nm, or lower wavelengths, and most preferably, it is donewith ultraviolet light of 157 nm or lower wavelengths. Imagewiseexposure can either be done digitally with a laser or equivalent deviceor non-digitally with use of a photomask. Suitable laser devices forimaging of the compositions of this invention include, but are notlimited to, an argon-fluorine excimer laser with UV output at 193 nm, akrypton-fluorine excimer laser with UV output at 248 nm, and a fluorine(F2) laser with output at 157 nm. These excimer lasers could be used fordigital imaging, but they are also the basis for non-digital imagingusing photomasks in optical steppers. Optical steppers for 248 nm canuse lamps or KrF excimer laser light sources, and at 193 and 157 nm thelight source is an excimer laser, 193 nm=ArF and 157 nm=F2 excimerlaser. Since, as discussed supra, use of UV light of lower wavelengthfor imagewise exposure corresponds to higher resolution the use of alower wavelength (e.g., 193 nm or 157 nm or lower) is generallypreferred over use of a higher wavelength (e.g., 248 nm or higher).

[0064] Development

[0065] The polymers suitable for use in the present invention can beformulated as a positive resist wherein the areas exposed to UV lightbecome sufficiently acidic to be selectively washed out with aqueousbase. Sufficient acidity is imparted to the copolymers by acid orprotected acid (which can be 100% in protected form prior to exposureprovided deprotection occurs during exposure to afford sufficient freeacid to provide for development) such that aqueous development ispossible using a basic developer such as sodium hydroxide solution,potassium hydroxide solution, or tetramethylammonium hydroxide solution.In this invention, a given copolymer for aqueous processability (aqueousdevelopment) in use is typically a carboxylic acid-containing and/orfluoroalcohol-containing copolymer (after exposure) containing at leastone free carboxylic acid group and/or fluoroalcohol group. The level ofacid groups (e.g., free carboxylic acid or fluoroalcohol groups) isdetermined for a given composition by optimizing the amount needed forgood development in aqueous alkaline developer.

[0066] When an aqueous processible photoresist is coated or otherwiseapplied to a substrate and imagewise exposed to UV light, the copolymerof the photoresist must have sufficient protected acid groups and/orunprotected acid groups so that when exposed to UV the exposedphotoresist will become developable in basic solution. In case of apositive-working photoresist layer, the photoresist layer will beremoved during development in portions which are exposed to UV radiationbut will be substantially unaffected in unexposed portions duringdevelopment by aqueous alkaline liquids such as wholly aqueous solutionscontaining 0.262 N tetramethylammonium hydroxide (with development at25° C. usually for less than or equal to 120 seconds) or 1% sodiumcarbonate by weight (with development at a temperature of 30° C. usuallyfor less than 2 or equal to 2 minutes). In case of a negative-workingphotoresist layer, the photoresist layer will be removed duringdevelopment in portions which are unexposed to UV radiation but will besubstantially unaffected in exposed portions during development usingeither a supercritical fluid or an organic solvent.

[0067] Halogenated solvents are preferred and fluorinated solvents aremore preferred.

[0068] In a further embodiment, the target surface may be an opticalsensor which produces an electronic, optical, or chemical signal inresponse to the incidentradiation such as in the signal or image wisereceiver in an optical, electo-optical or electronic detector used intime based,wavelength based or spatially resolved optical communicationssystems. In these cases the electromagnetic radiation incident on thetarget surface, and its time variation, spatial variation and/or itswavelength (spectral) variations can be used to encode information whichcan then be decoded at the detector. In another embodiment , the targetsurface may be a electro-optical receptor of the type used for light toenergy conversion. In another embodiment, the target surface may be aspecimen undergoing microscopic examination in the wavelength range of150-260 nm. In yet another embodiment, the target surface may be aluminescent surface caused to luminesce upon incidence of the 150-260 nmradiation employed in the method of the invention such as in a imagingsystem used as an optical imaging display. In another embodiment, thetarget surface may be a specimen undergoing materials processing, suchas laser ablation, laser trimming laser melting, laser marking in thewavelength range from 150 nm to 260 nm,

[0069] According to the method of the invention, a shaped articlecomprising a transparent, amorphous fluoropolymer as hereinbelowdescribed, is interposed between the light source and the target. In oneembodiment of the method of the invention the fluoropolymer of theinvention is employed in an adhesive. In another embodiment of themethod, the material is employed as a coating or an element to proventthe outgassing under irradiation of dissimilar materials in the systemso as to reduce optical contamination by more optically absorbingmaterials. In another embodiment the adhesivelike material is used as acoating or element or so as to capture and immobilize particulatecontaminants, to avoid their further migration and deposition in thesystem. In another embodiment the fluoropolymer is employed as a coatingon a non-optical element (such as a support structure in an opticalinstrument), an optical element (such as a mirror, a lens, a beamsplitter, a tuned etalon, a detetecor, a pellicle,). In a furtherembodiment, the fluoropolymer is itself a shaped article such as a lensor other optical element (such as a mirror, a lens, a beam splitter, atuned etalon, a detetecor, a pellicle,) or non optical component (suchas a support structure in an optical instrument). In the most preferredembodiment the fluoropolymer is in the form of a pellicle, afreestanding membrane mounted on a frame (which can be metallic, glass,polymer or other material) which is attached (adhesively or using othermethods such as magnetism) to the surface of a photomask employed in aphotolithographic process conducted in the wavelength region from 150 nmto 260 nm. More preferably, the photolithographic process employs alaser emitting radiation at 157 nm, 193 nm, or 248 nm. Most preferably,the photolithographic process employs a laser emitting 157 nm radiation.

[0070] In the apparatus of the invention is employed an activateablelight source of the type described hereinabove as suitable for use inthe method of the invention. By “activateable” is meant that the lightsource may be, in conventional terms, “on” or “off” but if in the “off”state may be turned on by conventional means. This light source may alsohave multiple wavelengths (as is used in wavelength divisionmultiplexing in optical communications) through the use of lamps ormultiple lasers of different wavelengths. Thus encompassed within theapparatus of the invention is a light source which may be “off” when sodesired, as when the apparatus is not being used, or is being shipped.However, the light source of the invention can be activated -- that is,turned “on”-- when it is desired to use it as, for example, in themethod of the present invention. When turned “on” or activated, thelight source emits electromagnetic radiation in the wavelength rangefrom 150 nm-260 nm. Light sources suitable for use in the apparatus ofthe invention include a lamp (such as a mercury or mercury-xenon lamp, adeuterium lamp or other gas discharge lamp of either the sealed orflowing gas type), an excimer lamp such as produces 172 nm radiation orother lamps), a laser (such as the excimer gas discharge lasers whichproduce 248 nm electromagnetic radiation from KrF gas, 193 nm radiationfrom ArF gas or 157 nm from F2 gas, or frequency up converterd as by nonlinear optical processes of laser whose emission in in the ultraviolet,visible or infrared), a black body light source at a temperature of atleast 2000 degrees Kelvin , an example of such a black body light sourcebeing a laser plasma light source where by a high powered laser isfocused to a small size onto a metal, ceramic or gas target, and aplasma is formed as for example in the samarium laser plasma lightsource whereby a black body temperature on the order of 250,000 degreesKelvin is achieved, and black body radiation from the infrared to thex-ray region can be produced) which emits radiation in the wavelengthrange from 150 nm to 260 nm. In a preferred embodiment, the source is aexcimer gas discharge laser emitting at 157 nm, 193 nm, or 248 nm, mostpreferably, 157 nm.

[0071] Further employed in the apparatus of the invention is a shapedarticle comprising the fluoropolymer of the invention, hereinbelowdescribed. In the apparatus of the invention, the shaped article isdisposed to lie within the path of electromagnetic radiation emittedfrom the souce when the source is activated or “turned on.” In oneembodiment of the apparatus of the invention the shaped article employsthe fluoropolymer of the invention in an adhesive. In another embodimentthe fluoropolymer is employed as a coating on an optical or non-opticalelement. In a further embodiment, the fluoropolymer is itself formedinto a shaped article such as a lens or other optical component. In themost preferred embodiment the fluoropolymer is in the form of apellicle, a protective film typically 0.6 to 1 micron thick that ismounted on a frame that is attached in turn to the surface of aphotomask employed in a photolithographic process conducted in thewavelength region from 150 nm to 260 nm.

[0072] While one of skill in the art will appreciate that the method ofuse contemplated for the apparatus of the invention necessarilycomprises a target surface of some sort, the apparatus of the inventionneed not encompass a target surface. For example, the apparatus of theinvention could be employed as a portable or transportable opticalirradiation system with a light source and a set of optical componentswhich could be used on a variety of target surfaces in severallocations.

[0073] Pellicle film thickness can be optimized such that the pelliclewill exhibit a thin film interference with a maximum in the in thetransmission spectrum at the desired lithographic wavelength. Thespectral transmission maximum of a properly tuned etalon pellicle filmoccurs where the spectral reflectance of the pellicle film exhibits aminimum.

[0074] Polymers suitable for the practice of the invention exhibit verylow absorbance/micron, at least <1, preferably <0.5, more preferably<0.1, and most preferably <0.01. Those which further exhibit values ofthe index of refraction which match the index of adjacent opticalelements have important uses antireflective index matching materials andoptically clear index matching adhesives, those which exhibitintermediate values of the index of refraction between those of anoptical element and either the ambient (with an index of 1 for example)or a second adjacent element of a different index of refraction haveimportant applications as anti-reflection coatings and those have a lowvalue of the index of refractions below 1.8, or preferably below 1.6 ormore preferably below 1.45 have very important applications asmultilayer anti-reflection coatings. Such polymers can be used to reducethe light reflected from the surface of a transparent substrate of arelatively higher index of refraction. This decrease in the reflectedlight, leads to a concomitant increase in the light transmitted throughthe transparent substrate material.

[0075] The polymers suitable for the practice of the present inventionmay be homopolymers or copolymers. The suitable homopolymer is selectedfrom group A. Suitable copolymers are selected from groups B, C, and Dwherein

[0076] group A consists of the homopolymer of CH₂=CFCF₃

[0077] group B consists of copolymers comprising >25 mole % of monomerunits derived from CF₂=CHOR_(f) in combination with monomer unitsderived from vinylidene fluoride wherein R_(f) is a linear or branchedC1 to C6 fluoroalkyl radical having the formula C_(n)F_(2n−y+1)H_(y)wherein the number of hydrogens is less than or equal to the number offluorines, no more than two adjacent carbons atoms are bonded tohydrogens, and ether oxygen can replace one or more of the carbonsproviding at least one of the carbons adjacent to any ether oxygen isperfluorinated;

[0078] group C consists of copolymers comprising >10 mole % of monomerunits derived from CH₂=CFCF₃, CF₂=CHOR_(f), or a mixture thereof incombination with monomer unit derived from 1,3 perfluorodioxoles whereinR_(f) is a linear or branched C1 to C6 fluoroalkyl radical having theformula C_(n)F_(2n−y+1) H_(y) wherein the number of hydrogens is lessthan or equal to the number of fluorines, no more than two adjacentcarbons atoms are bonded to hydrogens, and ether oxygen can replace oneor more of the carbons providing at least one of the carbons adjacent toany oxygen is perfluorinated, and wherein said 1,3-perfluorodioxole hasthe structure

[0079] wherein R_(a) and R_(b) are independently F or linear−C_(n)F_(2n+1), optionally substituted by ether oxygen, for which n=1 to5.

[0080] group D consists of copolymers comprising 40 to 60 mole % ofmonomer units derived from a monomer represented by the formula

[0081] in combination with monomer units derived from vinylidenefluoride and or vinyl fluoride wherein G and Q are independently F (butnot both F), H, R_(f), or -OR_(f) wherein R_(f) is a linear or branchedC1 to C5 fluoroalkyl radical having the formula C_(nF) _(2n−y+1) H_(y)wherein the number of hydrogens is less than or equal to the number offluorines, no more than two adjacent carbons atoms are bonded tohydrogens, and ether oxygen can replace one or more of the carbonsproviding that at least one of the carbons adjacent to any ether oxygenis perfluorinated.

[0082] The polymers suitable for the practice of the present inventionare useful in the manufacture of transmissive and reflective opticalelements, such as lenses and beam splitters mirrors and etalons, for usein the vacuum UV region.

[0083] The polymers suitable for the present invention may also be usedas elements in a compound lens designed to reduce chromatic aberrations.At present only CaF2 and possibly hydroxyl free silica are viewed ashaving sufficient transparency at 157 nm to be used in transmissivefocussing elements. It is also commonly known (e.g, see R. Kingslake,Academic Press, Inc., 1978, Lens Design Fundamentals, p. 77) that byusing a second material of different refractive index and dispersion, anachromatic lens can be created. Thus, by using one of these materials inconjunction with CaF2, it is expected that an achromatic lens can beconstructed from this and other similar materials described in thisapplication.

[0084] An additional area in which polymers play a critical role is asthe photosensitive photoresist which captures the optical latent image.In the case of photoresists, light must penetrate the full thickness ofthe resist layer for a latent optical image, with well defined verticalside walls to be produced during optical imaging which then will producethe desired resist image in the developed polymer. When used as a resistat 157 nm, a polymer can have a considerably higher absorptioncoefficient of A <˜2-3 per micrometer of film thickness, if the resistthickness is limited to about 2000 Å.

[0085] As used herein, the term amorphous fluoropolymer means afluoropolymer that exhibits no melting point when analyzed byDifferential Scanning Calorimetry. No melting point means no meltingassociated thermal event of greater than 1 Joule/gram.

[0086] Listing a monomer as a precursor to transparent polymers is notmeant to imply that it will either homopolymerize or form a copolymerwith any other listed monomer. Hexafluoroisobutylene for example, doesnot form useful homopolymer or copolymerize with tetrafluoroethyleneunder ordinary conditions. While these materials are being claimed foruse at 150 to 260 nm, they also make excellent clear polymers at longerwavelengths, up to 800 nm, and may also be suitable for someapplications at still shorter wavelengths.

[0087] Syntheses of R1R2C=CH2 monomers are well known in the art.R1=CF3, R2=C2F5 has been made by treating2-trifluoromethyl-3-chloro-4,4,4-trifluoro-2-butenyl p-toluenesulfonatewith KF Ltd.).(Japanese Patent Application JP 95-235253). R1=R 2=CF2Hhas been made by treating (HCF2)2C(OH)Me with SF4 (U.S. Pat. No.3655786). R1=CF3, R2=CF2H and R1=R2=CF2CI have been made by reacting thecorresponding fluoroalcohol R1C(OH)MeR2 with PCl5 (German Patent1945614). R1R2C=CH2 can also be made by methods developed forhexafluoroisobutylene such as heating (CF3)2CMeCOF with metal halides(Japanese Patent Application JP 93-312470), by reacting (CF3)2CHCOOMewith HCHO in the presence of amines (Japanese Patent Application JP86-52298), by reacting hexafluoroacetone with acetic anhydride at hightemperatures (U.S. patent 3,894,097, Allied Corp. USA), by the reactionof (CF3)2C(OH)2 with acetic anhydride at high temperatures (GermanPatent Application DE 84-3425907), and by the reaction of (CF3)2CHCH20Hwith base (S. Misaki, S. Takamatsu, J. Fluorine Chem., 24(4), 531-3(1984). In one embodiment of the invention are employed copolymers ofCF2=CHORf with vinylidene fluoride (VF2) and perfluoro-1,3-dioxoleswhere Rf is defined as a linear or branched C1 to C6C_(n)F_(2n−y+1)H_(y)group in which the number of hydrogens is less than or equal to thenumber of fluorines, no more than two adjacent carbons atoms are bondedto hydrogens, and ether oxygen can replace one or more of the carbonsproviding at least one of the carbons adjacent to any ether oxygen isperfluorinated. The monomers can be present in any ratio as long as thecontent of VF2 is not so high as to introduce crystallinity (more thanabout 75% VF2) or the PDD content so high as to make for low solubility(more than about 90% PDD).

[0088] Monomers such as vinylidene fluoride, PDD, and2,3,3,3-tetrafluoropropene -1 are items of commerce either as puremonomers or incorporated in commmercial polymers. Numerous substitutedperfluoro-1,3-dioxoles are described in J. Sheirs, editor, ModernFluoropolymers, John Wiley and Sons, West Sussex, England, 1997, p. 400.Monomers CF2=CHORA where RA is a linear or branched C2 to C20 carbongroup substituted with H, F, and other elements has been reported in USPat. No. 6,300,526B1, along with a general synthetic method thatinvolves the reaction of a 2-halo-2,2-difluoroethylic alcohol with afluorinated olefin in the presence of an alkaline or alkaline earthhydroxide followed by dehydrohalogenation. The monomer CF2=CHOCF2CF2Hwas made by reacting TFE with CICF2CH20H and KOH to give theCICF2CH20CF2CF2H adduct which was then dehydrochlorinated with base andheat. CF30CH=CF2 has been reported by Paul D. Schuman, Sci. Tech.Aerospace Rept. 1966, 4(6), N66-15770. Higher homologs RfOCH=CF2 inwhich Rf is a perfluoroalkyl group should be available by combining thehypofluorite/dehydrohalogenation chemistries in EP 0683 181 Al withNavarrini, et. al., J. Fluorine Chem., 95, 27(1999). An alternativemethod of making RfOCH=CF2 was developed here to avoid the difficultiesof making and working with hypofluorites: ester formation, fluorinationwith SF4, and dehydrohalogenation. 2,3,3,3-tetrafluoropropene-1homopolymer has been reported (D. Brown, L. Wall, Polym. Prepr., Amer.Chem. Soc., Div. Polym. Chem. 1971, 12, 1, pgs. 302-304) and2,3,3,3-tetrafluoropropene has been reported to copolymerize with avariety of other fluorocarbon and hydrocarbon monomers (US 5637663, JP09288915 A2 19971104).

[0089] The starting material for the CH2=C(CF3)CF20R family of monomersis hexafluoroisobutylene fluorosulfate, CH2=C(CF3)CF2OSO2F.Hexafluoroisobutylene fluorosulfate is made by the reaction ofhexafluoroisobutylene with sulfur trioxide in the presence of B(OC2H5)3catalyst. Alkoxide anions RO- can then be used to displace thefluorosulfate group in hexafluoroisobutylene fluorosulfate giving thedesired CH2=C(CF3)CF20R monomers. This chemistry can be run in dry,aprotic solvents that support alkoxide anion formation and that dissolvethe hexafluroroisobutyene fluorosulfate. Possible solvents includediethylene glycol dimethyl ether, tetramethylene sulfone, andacetonitrile with diethyleneglycol dimethyl ether being preferred.Reaction temperatures range from −50° C. to 100° C. A preferred reactiontemperature is from −25 to +25° C., preferably from −15 to −5° C. Whilehydrocarbon, fluorohydrocarbon, or fluorocarbon alkoxides can be usedfor the displacement of the fluorosulfate group, high UV transparencyresults when R is a linear or branched C1 to C6 fluoroalkyl radicalhaving the formula C_(n)F_(2n−y+1) H_(y) wherein the number of hydrogensis less than or equal to the number of fluorines, no more than twoadjacent carbons atoms are bonded to hydrogens, and ether oxygen canreplace one or more of the carbons providing at least one of the carbonsadjacent to any ether oxygen is perfluorinated. Polymers produced fromthe above monomers may be prepared as follows. Polymer synthesis can bedone by any of the nonaqueous or aqueous emulsion techniques well knownto fluoroolefin polymerizations. In nonaqueous polymerization, anautoclave is most frequently charged with solvent, initiator, andmonomers. The solvent is typically a fluid that does not interfere withthe growing radical chain: this can include neat monomer, compressedgases such as carbon dioxide, or more conventionally, fluids such asVertrel™ XF (CF3CFHCFHCF2CF3), Solkane™ 365 mfc (CF3CH2CF2CH3), Freon™113 (CF2CICCI2F), perfluorooctane, or Fluoriner™ FC-75. A great varietyof radical sources are known to initiate fluorolefin polymerizationsincluding diacyl peroxides, dialkyl peroxides, hydroperoxides,peroxyesters, percarbonates, azo compounds, NF3, and highly stericallyhindered perfluorocompounds for which appropriate initiationtemperatures vary from ˜0 to 300*C. In the the present inventionpreferred initiators are perfluorodiacylperoxides such as DP orperfluoropropionyl peroxide. In the case of DP, polymerizations can berun at 10 to 50*C, more preferably at 20 to 35*C. In the case of gaseousmonomers such as vinylidene fluoride, typically enough monomer is addedto generate an internal pressure of 50 to 1000 psi at operatingtemperature. These polymers can also be made by aqueous emulsionpolymerization using initiators such as potassium persulfate or Vazo™ 56WSP [2,2′-[2,2′-azobis(2-amidinopropane)dihydrochloride] in the presenceof surfactant. But the introduction of possibly contaminatingsurfactants and end groups can make emulsion polymerization undesirablefor high UV transparency. In the case of the particular polymers beingmade here, the CH2=C(CF3)CF20R content in the final polymers should beabout 40 to 60 mole % because CH2=C(CF3)CF20R prefers to alternate andVF2 content should be ˜75 mole % or less since more VF2 leads tocrystallinity.

EXAMPLES

[0090] Abbreviations employed herein include:

[0091] HFIB hexafluoroisobutylene

[0092] PDD 4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole

[0093] DSC Differential scanning calorimetry

[0094] H-Galden® ZT 85 A trademark of Ausimont,HCF2O(CF2O)n(CF2CF2O)mCF2H

[0095] DP: hexafluoropropyleneoxide dimer peroxide of structure

[0096] CF₃CF₂CF₂0CF(CF₃)(C=O)OO(C=O)CF(CF₃)OCF₂CF₂CF₃

[0097] Novec™ HFE-7500, a product of 3M, CF₃CF(CF₃)CF(OC₂H₅)CF₂CF₂CF₃

[0098] Vertrel® XF, a product of DuPont, CF₃CFHCFHCF₂CF₃

[0099] HFIB Fluorosulfate: CH₂=C(CF₃)CF₂OSO₂F or 3,3-dihydro-2-trifluoromethylperfluoroallyl fluorosulfate

[0100] The absorbance/micron of was measured for polymer filmsspin-coated on to CaF2 substrates using standard methods in the art asdescribed in R. H. French, P. C. Wheland, D. J. Jones, J. N. Hilfiker,R. A. Synowicki, F. C. Zumsteg, J. Feldman, A. E. Feiring,“Fluoropolymers for 157 nm Lithography: Optical Properties from VUVAbsorbance and Ellipsometry Measurements”, Optical MicrolithographyXIII, SPIE Vol. 4000, edited by C. J. Progler, 1491-1502 (2000). The VUVtransmission of each CaF2 substrate was measured prior to the spincoating of the polymer film. Then the VUV transmission of the polymerfilm on that particular CaF2 substrate was measured. using a VUV-Vasemodel VU-302 spectroscopic ellipsometer, which is capable of performingtransmission measurements, made by J. A. Woollam Inc. (J.A. Woollam Co.,Inc. Lincoln, Nebr. The film thickness was determined using a Filmetrics(Filmetrics Inc., San Diego, Calif. model F20 thin film measurementsystem. Using Equation 1, the spectral transmission and the filmthickness, the values of the absorbance/micron for the polymers werecalculated from 145 nm to longer wavelengths, including at 157, 193, and248 nm.

[0101] Optical properties (index of refraction, “n” and extinctioncoefficient, “k”) are determined from variable angle spectroscopicellipsometry (VASE) at three incident angles covering the wavelengthrange from 143-800 nm, corresponding to an energy range of 1.5-8.67 eV.The polymer films were spin coated onto a silicon substrate. The VASEellipsometer was manufactured by J. A. Woollam Company, 645 M Street,Suite 102, Lincoln, Nebr. 68508 USA. Optical constants were fit to thesedata simultaneously, using an optical model of the film on thesubstrate. See generally, O. S. Heavens, Optical Properties of ThinSolid Films, pp. 55-62, Dover, N.Y., 1991.

Example 1 Poly[(CH₂=C(CF₃)CF₂0CH(CF₃)₂/CH₂=CF₂] 1

[0102] A. Preparation of1,1,5-trihydro-2,5-bis(trifluoromethyl)-4-oxo-perfluoro-1- hexene,CH₂=C(CF₃)CF₂0CH(CF₃)₂ monomer

[0103] A 100 ml flask was charged with tributylamine (15 g), diglyme (15ml), and hexafluoroisopropanol (13.7 g) in a dry box. HFIB fluorosulfate(20.0 g) was added dropwise at 3 - 12° C. The resulting mixture wasstirred at room temperature for 2 hours. The mixture was fresh distilledto give a liquid, which was then spinning band distilled to afford 21.1g product, bp 92-3° C., yield 83 %. (Less pure fractions were notcounted.) 19F NMR (CDCI3) -65.3 (t, J=7 Hz, 3F), -70.8 (m, 2F), -74.0(q, J =5 Hz, 6F) ppm. 1H NMR (CDCI3) 4.99 (septet, J=5 Hz, 1H), 6.37 (m,2H) ppm. 13C NMR (CDCI3) 69.4 (septet, t, J=35, 4 Hz), 118.8 (t, J=269Hz), 120.2(q, J=283 Hz), 120.6 (sextet, J=5 Hz), 130.9 (sextet, J=35 Hz)ppm.

[0104] B. CH₂=C(CF₃)CF₂OCH(CF₃)₂ copolymerization with CH₂=CF₂

[0105] A 75 ml stainless steel autoclave chilled to <−20° C. was loadedwith 11.6 g of CH₂=C(CF₃)CF₂OCH(CF₃)₂ monomer, 10 ml of CF₃CH₂CF₂CH₃solvent, and 10 ml of ˜0.17 M DP in CF₃CFHCFHCF₂CF₃. The autoclave waschilled, evacuated and further loaded with ˜2 g of vinylidene fluoride.The autoclave was shaken overnight at room temperature. The resultinghazy fluid was dried under nitrogen, then under pump vacuum, and finallyfor 66 hours in a 75° C. vacuum oven, giving 12.9 g of white polymer.Fluorine NMR in hexafluorobenzene found 53.4 mole % vinylidene fluorideand 46.6 mole % CH₂=C(CF₃)CF₂OCH(CF₃)₂. Inherent viscosity inhexafluorobenzene at 25° C. was 0.116 dLg. A small sample was purifiedfor DSC measurements by dissolving 0.5 g of polymer in 3 g of H GaldenZT 85 solvent [HCF20(CF20)m(CF2CF20)nCF2H], filtering the haze off usinga 0.45 micron PTFE syringe filter (Whatman Autovial®), evaporating offexcess solvent, and drying in a 75° C. vacuum oven for 16 hours. The Tgwas now 47° C. (10° C./min, N₂, second heat).

[0106] C. Solution preparation

[0107] A hazy solution was made by rolling 2 g of polymer with 18 g of HGalden™ ZT 85 solvent. The haze was removed by filtering first through abed of chromatographic silica in a 0.45μ glass fiber microfiber syringefilter (Whatman Autovial™), centrifuging at 15000 rpm, and finallyfiltering again through a 0.2 μ PTFE syringe filter (Gelman AcrodiscCR). Evaporation of 0.1192 g of this solution on a glass slide gave aclear film weighing 0.0085 g (solution ˜7wt % in solids).

[0108] D. Optical characterization Spinning of solution:

[0109] The polymer solution so prepared was spin coated in an enclosedvapor can spinner at spin speeds of 800 rpm for 30 seconds, after aninitial 10 second vapor equilibration period onto CaF2and siliconsubstrates with a subsequent post apply bake at 120 C for 2 minutes toproduce polymer films of 9200 angstroms thickness for VUV absorbancemeasurements and of 3523 angstroms thickness for VUV ellipsometrymeasurements. VUV absorbance measurements were then used to determinethe absorbance per micrometer and VUV ellipsometry measurements of thefilms on silicon were used to determine the index of refraction.

[0110] Optical Results:

[0111] The absorbance in units of inverse micrometers for the polymerfilm so prepared versus wavelength lambda (λ) in units of nanometers isshown in FIG. 1. The 157 nm absorbance/micrometer determined was0.011/micrometer. The 193 nm absorbance/micrometer determinedwas-0.002/micrometer. The 248 nm absorbance/micrometer determinedwas-0.002/micrometer.

[0112] The index of refraction for Polymer 1 versus wavelength lambda(λ) in units of nanometers is shown in FIG. 2. The 157 nm index ofrefraction determined is 1.45. The 193 nm index of refraction determinedis 1.40. The 248 nm index of refraction is 1.37.

Example 2 Poly[(CH₂=C(CF₃)CF₂OCF(CF₃)₂/CH₂=CF₂] 2

[0113] Preparation of1,1-dihydro-2,5-bis(trifluoromethyl)-4-oxo-perfluorohex-1-ene,CH₂=C(CF₃)CF₂0CF(CF₃)₂ monomer A 250 ml flask was charged with KF (12 g)and diglyme (55 ml) in a dry box. Hexafluoroacetone (40.5 g) was addedto the mixture via a dry-ice condenser. The solid was dissolvedcompletely. The HFIB fluorosulfate (49 g) was added dropwise. Theresulting mixture was stirred at room temperature for 3 hours. Themixture was fresh distilled to give a liquid, which was then spinningband distilled to afford 36.3 g product, bp 84-86° C., yield 55%. (Lesspure fractions were not counted.) 19F NMR (CDCI3) -65.3 (t, J=8 Hz, 3F),-66.6 (m, 2F), -81.0 (m, 6F), -146.4 (t, J=23 Hz,1F) ppm. 1H NMR (CDCI3)6.39 (m) ppm.13C NMR (CDCI3) 101.5 (d&septet, J =269, 38 Hz), 117.7 (qd,J =258, 32 Hz), 118.6 ( t, J 274 Hz), 127.4 (m), 131.2 (m) ppm. B.CH₂=C(CF₃)CF₂OCF(CF₃)₂ copolymerization with CH₂=CF₂ A 110 ml stainlesssteel autoclave chilled to <−20° C was loaded with 26 g ofCH₂=C(CF₃)CF₂OCF(CF₃)₂ monomer, 25 ml of CF₃CFHCFHCF₂CF₃ solvent, and 10ml of ˜0.17 M DP in CF₃CFHCFHCF₂CF₃. The autoclave was chilled,evacuated and further loaded with ˜5 g of vinylidene fluoride. Theautoclave was shaken overnight at room-temperature. The resultingviscous fluid was dried under nitrogen, then under pump vacuum, andfinally for 88 hours in a 75° C. vacuum oven, giving 26.7 g of whitepolymer. Fluorine NMR run in hexafluorobenzene found 51 mole%CH₂=C(CF₃)CF₂OCF(CF₃)₂ and 49 mole % CH₂=CF₂.

[0114] DSC, 10° C./min, N₂, 2nd heat neither Tg nor Tm detected InherentViscosity, hexafluorobenzene, 25° C.: 0.083

[0115] C. Solution preparation

[0116] A clear, colorless solution was made by rolling 2 g of polymerwith 18 g of H Galden™ ZT 85 solvent and passing through a 0.45μ glassfiber microfiber syringe filter (Whatman Autovial™).

[0117] D. Optical characterization

[0118] Spinning of solution:

[0119] The polymer solution so prepared was spin coated in aconventional atmosphere spinner at spin speeds of 90 rpm for theabsorbance sample and 500 rpm for the ellipsometry sample for 30 secondsonto CaF2and silicon substrates with a subsequent post apply bake at 120C. for 2 minutes to produce polymer films of 10800 angstroms thicknessfor VUV absorbance measurements and of 3757 angstroms thickness for VUVellipsometry measurements. VUV absorbance measurements of the films onCaF₂ were then used to determine the absorbance per micrometer and VUVellipsometry measurements of the films on silicon were used to determinethe index of refraction.

[0120] Optical results:

[0121] The absorbance in units of inverse micrometers for the polymerfilm so prepared versus wavelength lambda (λ) in units of nanometers isshown in FIG. 2. The 157 nm absorbance/micrometer determined was 0.0275micrometer. The 193 nm absorbance/micrometer determined was 0.0045micrometer. The 248 nm absorbance/micrometer determined was 0.0008micrometer.

[0122] The index of refraction for Polymer 2 versus wavelength lambda(λ) in units of nanometers is shown in FIG. 4. The 157 nm index ofrefraction determined is 1.44. The 193 nm index of refraction determinedis 1.39. The 248 nm index of refraction is 1.37.

Example 3 Poly(CF₂=CHOCF₂CF₂H/CH₂=CF₂) 3 A. Preparation of1,1,2,2-tetrafluoroethyl 2,2-difluorovinyl ether, CF₂=CHOCF₂CF₂Hmonomer.

[0123] a/Preparation of 1,1,2,2-Tetrafluoroethyl2-chloro-2,2-difluoroethyl ether

[0124] A mixture of 2-chloro-2,2-difluoroethanol (22.0 g), t-butanol(45mi), KOH (10.0 g) and TFE (25 g) was shaken at room temperature for 8hours in a autoclave. The bottom layer of the reaction mixture wasisolated and washed with water (40 ml) to give a crude product,1,1,2,2-Tetrafluoroethyl 2-chloro-2,2-difluoroethyl ether, 29.5 g, yield72%. This product was used for next step without further purification.

[0125] b/ Preparation of 1,1,2,2-Tetrafluoroethyl 2,2-difluorovinylether A mixture of 1,1,2,2-Tetrafluoroethyl 2-chloro-2,2-difluoroethylether (29.0 g), KOH (10.0 g), and DMSO (5 ml) was heated to reflux on aspinning band distillation apparatus. The product was distilled out togive 9.6 g of 1,1,2,2-Tetrafluoroethyl 2,2-difluorovinyl ether, bp 38°C., yield 40%.

[0126] 19F NMR (CDCI3)-92.3 (s, 2F), -92.7 (ddt, J=57, 14, 3 Hz, 1F),-110.5 (dd, J=54, 3 Hz, 1F),-137.4 (dt, J=52, 5 Hz, 2F) ppm. 13C NMR(CDCI3) 98.9 (dd, J=61, 16 Hz), 107.2 (tt, J=252, 40 Hz), 116.3 (ft,J=273, 40 Hz), 157.0 (dd, J=293, 281 Hz) ppm. 1 H NMR (CDCI3) 5.84 (ft,J=52,3 Hz, 1 H), 6.10 (dd, J=13,4 Hz, 1 H) ppm. B. CF₂=CHOCF₂CF₂Hcopolymerization with CH₂=CF₂ A 75 ml stainless steel autoclave chilledto <-20° C was loaded with 9.4 g of CF₂=CHOCF₂CF₂H monomer, 10 ml ofCF₃CFHCFHCF₂CF₃ solvent, and 5 ml of ˜0.17 M DP in CF₃CFHCFHCF₂CF₃. Theautoclave was chilled, evacuated and further loaded with ˜4 g ofvinylidene fluoride. The autoclave was shaken overnight at roomtemperature. The resulting hazy fluid was dried under nitrogen, thenunder pump vacuum, and finally for 23 hours in a 77° C. vacuum oven,giving 4.6 g of tacky gum.

[0127] Calc. for (C₂H₂F₂ )₃(C₄H₂F₆O)₂:30.45% C 1.83% H Found: 30.65% C1.41% H DSC, 10° C./min, N₂, 2nd heat Tg @ −11° C. Inherent Viscosity,acetone, 25° C.: 0.122

[0128] C. Solution preparation

[0129] A clear, colorless solution was made by rolling 2.5 g of polymerwith 10 g of 2-heptanone solvent and passing through a 0.45μ glass fibermicrofiber syringe filter (Whatman Autovial™).

[0130] D. Optical characterization Spinning of solution:

[0131] The polymer solution so prepared was spin coated in aconventional atmosphere spinner at spin speeds of 1000 rpm for 60seconds onto CaF2 and silicon substrates with a subsequent bake at 120C. for 2 minutes to produce polymer films of 900 angstroms thickness.VUV absorbance measurements were then used to determine the absorbanceper micrometer and VUV ellipsometry measurements of the films on siliconwere used to determine the indexof refraction.

[0132] The absorbance in units of inverse micrometers for the polymerfilm so prepared versus wavelength lambda (λ) in units of nanometers isshown in FIG. 5. The 157 nm absorbance/micrometer determinedwas-0.002/micrometer. The 193 nm absorbance/micrometer determinedwas-0.001/micrometer. The 248 nm absorbance/micrometer determined was0.003/micrometer.

[0133] The index of refraction versus wavelength lambda (λ) in units ofnanometers was shown in FIG. 6. The 157 nm index of refractiondetermined was 1.48. The 193 nm index of refraction determined was 1.42.The 248 nm index of refraction was 1.39.

Example 4 Poly(CF₂=CHOCF₂CF₂H/PDD) 4

[0134] A. CF₂=CHOCF₂CF₂H copolymerization with PDD

[0135] A ˜30 ml glass sample vial containing a magnetic stir bar wascapped with a rubber septum, flushed with nitrogen, and chilled on dryice. The sample vial was then injected with 5 g of CF₂=CHOCF₂CF₂Hmonomer, 6.8 g of PDD monomer, and 1 ml of ˜0.17 M DP inCF₃CFHCFHCF₂CF₃. After flushing the vial once again with nitrogen, thecontents of the vial were allowed to warm slowly to room temperaturewith magnetic stirring. By the next morning the reaction mixture washazy and viscous. Another 1 ml of ˜0.17 M DP in CF₃CFHCFHCF₂CF₃ wasinjected and the reaction mixture stirred another 4 days at roomtemperature. The contents of the vial were poured into ˜125 ml of hexaneand the precipitate isolated by vacuum filtration giving 8.6 g ofcrumbly white solid.

[0136] Calc. for (C₄F₆OH₂)₁( C₅F₈O₂)₂: 25.17 % C 0.30% H

[0137] Found: 24.97 % C 0.56 % H

[0138] DSC, 10° C./min, N₂, 2nd heat Tg @ 25° C.

[0139] Inherent Viscosity, hexafluorobenzene, 25° C.: 0.126

[0140] C. Solution preparation

[0141] A clear, colorless solution was made by rolling 2.5 g of polymerwith 10 g of Novec™ HFE-7500 solvent and passing through a 0.45μ glassfiber microfiber syringe filter (Whatman Autovial™). D. OpticalcharacterizationThe polymer solution so prepared was spin coated in aconventional atmosphere spinner at spin speeds of 2000 rpm for theabsorbance sample and 800 rpm for the ellipsometry sample for 30 secondsonto CaF2 and silicon substrates with a subsequent post apply bake at120 C for 2 minutes to produce polymer films of 11200 angstromsthickness for VUV absorbance measurements and of 6272 angstromsthickness for VUV ellipsometry measurements. VUV absorbance measurementsof the films on CaF₂ were then used to determine the absorbance permicrometer and VUV ellipsometry measurements of the films on siliconwere used to determine the index of refraction.

[0142] The absorbance in units of inverse micrometers versus wavelengthlambda (λ) in units of nanometers is shown in FIG. 7. The 157 nmabsorbance/micrometer determined was 0.055/micrometer. The 193 nmabsorbance/micrometer determined was 0.014/micrometer. The 248 nmabsorbance/micrometer determined was 0.008/micrometer.

[0143] The index of refraction for Polymer 4 versus wavelength lambda(λ) in units of nanometers is shown in FIG. 8. The 157 nm index ofrefraction determined was 1.41. The 193 nm index of refractiondetermined was 1.36. The 248 nm index of refraction was 1.35.

Example 5 Poly(CF₂=CHOCF₂CF_(3/)CH₂=CF₂) 5 A. Preparation ofperfluoroethyl 2,2-difluorovinyl ether, CF₂=CHOCF₂CF₃ monomer.

[0144] a) Preparation of 2-chloro-2,2-difluoroethyl trifluoroacetate.

[0145] A mixture of 2-chloro-2,2-difluoroethanol (132 g) and DMF (15drops) was charged to a 250 ml flask. Trifluoroacetyl chloride (17 g)was introduced to the flask via a dry ice condenser at about 50° C. Theresulting mixture was refluxed for 4 hours. The mixture was distilled togive 234 g of the acetate, bp 79-81° C., yield 97%. 19F NMR (CDCI3)-62.8 (t, J=8 Hz, 2F), -75.2 (s, 3F) ppm. 1 H NMR (CDCI3) 4.79 (t, J=9Hz) ppm.

[0146] b) Preparation of perfluoroethyl 2-chloro-2,2-difluoroethylether.

[0147] A mixture of 2-chloro-2,2-difluoroethyl trifluoroacetate (20 g),HF (150 g), and SF₄ (60 g) was heated to 150° C. for 21 hours. Themixture was poured into water (300 ml). The bottom layer was isolated togive crude product (16.1 g), yield 73%. It was relatively pure based onNMR analysis. Then the crude product was washed with Na2CO3 until pH=8,dried over Na2SO4, and distilled to afford the product, 11 g, bp 54-55°C., yield 50%.19F NMR (CDCI3) -63.5 (tt, J=9, 3 Hz, 2F), -86.4 (s,3F),-91.2 (s, 2F) ppm.

[0148] c) Preparation of Perfluoroethyl 2,2-difluorovinyl ether

[0149] A mixture of perfluoroethyl 2-chloro-2,2-difluoroethyl ether (69g), KOH (30.0 g) and DMSO (15 ml) was heated to reflux on a spinningband distillation apparatus. The product was distilled out to give 43 gof perfluoroethyl2,2- 2,2-difluorovinyl ether, bp 15° C., yield 85 %.19F NMR (CDCI3) -86.5 (s, 3F), -91.8 (dd, J=18, 4 Hz, 1F), -92.1 (s,2F), -109.3 (d, J=18Hz,1F) ppm. 1H NMR (CDCI3) 6.08 (dd, J=13,4Hz)ppm.13C NMR (CDCI3) 98.9 (m), (ddt, J =62,16, 5 Hz), 116.2 (qt, J=284,45Hz), 114.3 ( tq, J=275, 42 Hz), 156.3 (d, J 295 Hz) ppm. B.Copolymerization of CF₂=CHOCF₂CF₃ with CH₂=CF₂

[0150] A 75 ml stainless steel autoclave chilled to <−20° C. was loadedwith 10 ml of CF₃CFHCFHCF₂CF₃ solvent and 5 ml of ˜0.17 M DP inCF₃CFHCFHCF₂CF₃. The autoclave was chilled, evacuated and further loadedwith 10 g of CF₂=CHOCF₂CF₃ and ˜4 g of vinylidene fluoride. Theautoclave was shaken ovemight at room temperature. The resulting fluidwas dried under nitrogen, then under pump vacuum, and finally for 4 daysin a 77° C. vacuum oven, giving 2.6 g of tacky gum.

[0151] Calc. for (C₄F₇OH )₁₀( C₂H₂F₂)₁₁: 27.74% C 1.20% H

[0152] Found: 27.89% C 0.91% H

[0153] DSC, 10° C./min, N₂, 2nd heat Tg @ −5° C. C. Solution preparationA solution was made by rolling 1 g of polymer with 9 g of H Galden™ZT 85solvent and passing through a 0.45μPTFE fiber microfiber syringe filter(Whatman Autovial™) to remove haze.

[0154] D. Optical characterization

[0155] The polymer solution so prepared was spin coated in aconventional atmosphere spinner at spin speeds of 1000 rpm for theabsorbance sample and 800 rpm for the ellipsometry sample for 30 secondsonto CaF2 and silicon substrates with a subsequent post apply bake at120 C for 2 minutes to produce polymer films of 10200 angstromsthickness for VUV absorbance measurements and of 5880 angstromsthickness for VUV ellipsometry measurements. VUV absorbance measurementsof the films on CaF₂ were then used to determine the absorbancepermicrometer and VUV ellipsometry measurements of the films on siliconwere used to determine the index of refraction.

[0156] The absorbance in units of inverse micrometers for the polymerfilm so prepared versus wavelength lambda (=80 ) in units of nanometersis shown in FIG. 9. The 157 nm absorbance/micrometer determined was0.034/micrometer. The 193 nm absorbance/micrometer determined was0.02/micrometer. The 248 nm absorbance/micrometer determined was0.01/micrometer.

[0157] The index of refraction versus wavelength lambda (λ) in units ofnanometers is shown in FIG. 10. The 157 nm index of refractiondetermined was 1.47. The 193 nm index of refraction determined was 1.40.The 248 nm index of refraction was 1.38.

Example 6 Poly(CF₂=CHOCF₂CF₂CF₂CF_(3/)PDD) 6

[0158] A. Preparation of perfluorobutyl 2,2-difluorovinyl ether,CF₂=CHOCF₂CF₂CF₂CF₃ monomer.

[0159] a) Preparation of 2-chloro-2,2-difluoroethyl perfluorobutyrate.

[0160] A 100 ml flask was charged with 2-chloro-2,2-difluoroethanol (49g) and DMF (10 drops). Perfluorobutyryl chloride (100 g) was added tothe flask dropwise at about 50° C. The resulting mixture was heated at50° C for another 3 hours. The mixture gave 115 g of product, bp128-130° C., yield 88%.

[0161] b) Preparation of perfluorobutyl 2-chloro-2,2-difluoroethylether. A mixture of 2-chloro-2,2-difluoroethyl perfluorobutyrate (90 g),HF (500 g), and SF₄ (150g) was heated to 110° C. for 40 hours in anautoclave. Water (500 ml) was added to the reactor at 0° C. The bottomlayer was isolated and dried over MgSO4, and distilled to afford theproduct, 71 g, bp 98° C., yield 74%. 19F NMR (CDCI3) -63.5 (tt, J=10, 3Hz, 2F), -81.6 (t, J=10 Hz, 3 F), -86.2 (s, 2F), 126.6 (m, 2 F), 127.1(m, 2F) ppm. 1H NMR (CDC13) 4.42 (t, J=10 Hz) ppm.

[0162] c) Preparation of Perfluorobutyl 2,2-difluorovinyl ether.

[0163] A mixture of perfluorobutyl 2-chloro-2,2-difluoroethyl ether(42.2 g), KOH (50.0 g) and DMSO (0.5 ml) was heated to distill theproduct bp <68° C. The product was redistilled to give 30.8 g ofperfluorobutyl 2,2-difluorovinyl ether, bp 65° C., yield 82%. 19F NMR(CDCI3) -81.5 (t, J=10 Hz, 3F), -86.8 (s, 2F), -91.0 (ddt, J=52, 13, 3Hz, 1F), -108.7 (dd, J =52, 4 Hz, 1F), -126.6 (m, 2F), -127.1 (m, 2F)ppm. 1H NMR (CDCI3) 6.14 (dd, J=13,4 Hz) ppm.

[0164] B. CF₂=CHOCF₂CF₂CF₂CF₃ copolymerization with PDD

[0165] A ˜30 ml glass sample vial containing a magnetic stir bar and 5ml of CF₃CFHCFHCF₂CF₃ was capped with a rubber septum, flushed withnitrogen, and chilled on dry ice. The sample vial was injected with 6 gof CF₂=CHOCF₂CF₂CF₂CF₃ monomer, 4.88 g of PDD monomer, and 1 ml of ˜0.17M DP in CF₃CFHCFHCF₂CF₃, purging the vial with nitrogen after eachaddition. The contents of the vial were allowed to warm slowly to roomtemperature with magnetic stirring. By the next morning the reactionmixture was a thick gel. The contents of the vial were poured into ˜125ml of hexane and the lumpy precipitate isolated by decantation. The wetpolymer was dried by nitrogen purging, putting under pump vacuum, andfinally heating for 24 hours in a 80° C. vacuum oven. This gave 6.15 gof white lumps. Fluorine NMR found 77.5 mole % PDD and 22.5 mole %CF₂=CHOCF₂CF₂CF₂CF₃.

[0166] DSC, 10° C./min, N₂, 2nd heat Neither Tg, nor Tm detected.

[0167] C. Solution preparation

[0168] A clear, colorless solution was made by rolling 1 g of polymerwith 9 g of Novec™ HFE-7500 solvent for about 5 days and passing througha 0.45μglass fiber microfiber syringe filter (Whatman Autovial™).

[0169] D. Optical characterizationThe polymer solution so prepared wasspin coated in a conventional atmosphere spinner at spin speeds of 2000rpm for 30 seconds onto CaF2 and silicon substrates with a subsequentpost apply bake at 120 C for 2 minutes to produce polymer films of 11700angstroms thickness for VUV absorbance measurements and of 11492angstroms thickness for VUV ellipsometry measurements. VUV absorbancemeasurements of the films on CaF₂ were then used to determine theabsorbance per micrometer and VUV ellipsometry measurements of the filmson silicon were used to determine theindex of refraction.

[0170] The absorbance in units of inverse micrometers for the polymerfilm so prepared versus wavelength lambda (λ) in units of nanometers isshown in FIG. 11. The 157 nm absorbance/micrometer determined was0.022/micrometer. The 193 nm absorbance/micrometer determined was0.0015/micrometer. The 248 nm absorbance/micrometer determined was-0.001/micrometer.

[0171] The index of refraction versus wavelength lambda (λ) in units ofnanometers is shown in FIG. 12. The 157 nm index of refractiondetermined was 1.35. The 193 nm index of refraction determined was 1.30.The 248 nm index of refraction was 1.28.

Example 7 Poly(CH₂=CFCF₃) 7 A. Homopolymerization of2,3,3,3-Tetrafluoropropene-1

[0172] A 75 ml autoclave chilled to <−20° C. was loaded with 10 ml of˜0.17M DP in CF₃CFHCFHCF₂CF₃ solvent and 10 g of2,3,3,3-tetrafluoropropene -1. The reaction mixture was shakenovernight. The resulting solution was evaporated down under nitrogen,then for 24 hours under pump vacuum, and finally for 45 hours in a 75°C. vacuum oven. This gave 1.77 g of polymer.

[0173] DSC, 10° C./min, N₂, second heat Tg @ 390° C.

[0174] Inherent viscosity, acetone, 25° C. 0.029 dL/g

[0175] B. Solution Preparation

[0176] A solution was made by rolling 1.17 g of polymer with 10.53 g ofH Galden ZT 85 and filtering through a 0.45 μ glass fiber microfibersyringe filter (Whatman Autovial™).

[0177] C. Optical Characterization

[0178] Solutions of Polymer 7 were spin coated in a conventionalatmosphere spinner at spin speeds of 2000 rpm for the absorbance sampleand 800 rpm for the ellipsometry sample for 30 seconds onto CaF₂ andsilicon substrates with a subsequent post apply bake at 120 C. for 2minutes to produce polymer films of 7000 angstroms thickness for VUVabsorbance measurements and of 909 angstroms thickness for VUVellipsometry measurements. VUV absorbance measurements of the films onCaF₂ were then used to determine absorbance per micrometer and VUVellipsometry measurements of the films on silicon were used to determinethe index of refraction.

[0179] Optical results:

[0180] The absorbance in units of inverse micrometers for Polymer 7versus wavelength lambda (λ) in units of nanometers is shown in FIG. 13.The 157 nm absorbance/micrometer determined is 0.005/micrometer. The 193nm absorbance/micrometer determined is 0.007/micrometer. The 248 nmabsorbance/micrometer determined is 0.01/micrometer.

[0181] The index of refraction for Polymer 7 versus wavelength lambda(λ) in units of nanometers is shown in FIG. 14. The 157 nm index ofrefraction determined is 1.47. The 193 nm index of refraction determinedis 1.42. The 248 nm index of refraction is 1.38.

Example 8 Poly(CH2=CFCF3/PDD) 8 A. Copolymerization of2,3,3,3-tetrafluoropropene-1 with perfluoro-dimethyidioxole

[0182] A 75 ml autoclave chilled to <−20*C. was loaded with 5 ml of˜0.17 M DP in CF3CFHCFHCF2CF3 solvent, 12 g of perfluorodimethyldioxole,10 ml of CF3CFHCFHCF2CF3 (VertrelTM XF), and 11 9 of2,3,3,3-tetrafluoropropene -1. The reaction mixture was shaken overnightat room temperature. The resulting solution was evaporated down undernitrogen, put under pump vacuum for 3 days, and then finished by heatingfor 24 hours in a 75*C. vacuum oven. This gave 3.29 g of white lumps.

[0183] Calc. for (C3H2F4)5(C5F802)2: 28.37% C

[0184] 0.95% H

[0185] Found: 28.27% C

[0186] 0.99% H

[0187] Inherent viscosity, hexafluorobenzene,25*C. 0.042 B. Solutionpreparation (Wheland E101 100-54)

[0188] A solution was made by rolling 2.5 g of polymer with 10 g of HGalden ZT 85 and filtering through a 0.45 micron glass microfibersyringe filter (Whatman Autovial™). D. Optical characterization Spinningof solution:

[0189] Solutions of Polymer 8 were spin coated in a conventionalatmosphere spinner at spin speeds of 2000 rpm for the absorbance sampleand 800 rpm for the ellipsometry sample for 30 seconds onto CaF₂ andsilicon substrates with a subsequent post apply bake at 120 C. for 2minutes to produce polymer films of 10200 angstroms thickness for VUVabsorbance measurements and of 3583 angstroms thickness for VUVellipsometry measurements. VUV absorbance measurements of the films onCaF₂ were then used to determine the absorbance per micrometer and VUVellipsometry measurements of the films on silicon were used to determinethe index of refraction.

[0190] Optical results:

[0191] The absorbance in units of inverse micrometers for Polymer 8versus wavelength lambda (λ) in units of nanometers is shown in FIG. 15.The 157 nm absorbance/micrometer determined is 0.006/micrometer. The 193nm absorbance/micrometer determined is 0.004/micrometer. The 248 nmabsorbance/micrometer determined is-0.0004/micrometer.

[0192] The index of refraction for Polymer 8 versus wavelength lambda(λ) in units of nanometers is shown in FIG. 16. The 157 nm index ofrefraction determined is 1.46. The 193 nm index of refraction determinedis 1.41. The 248 nm index of refraction is 1.38.

What is claimed is:
 1. A method comprising causing a source to emitelectromagnetic radiation in the wavelength range from 150 nanometers to260 nanometers; disposing a target surface in the path of at least aportion of said electromagnetic radiation in such a manner that at leasta portion of said target surface will be thereby illuminated; and,interposing in the path of at least a portion of said electromagneticradiation between said target surface and said source a shaped articlecomprising a fluoropolymer exhibiting an absorbance/micrometer ≦1 atwavelengths from 150 to 260 nm and a heat of fusion of <1 J/g saidfluoropolymer being a homopolymer selected from group A or copolymersfrom groups B, C, and D wherein group A consists of the homopolymer ofCH₂=CFCF₃ group B consists of copolymers comprising >25 mole % ofmonomer units derived from CF₂=CHORf in combination with monomer unitsderived from vinylidene fluoride wherein Rf is a linear or branched Clto C6 fluoroalkyl radical having the formula C_(n)F_(2n−y+1)H_(y)wherein the number of hydrogens is less than or equal to the number offluorines, no more than two adjacent carbons atoms are bonded tohydrogens, and ether oxygen can replace one or more of the carbonsproviding at least one of the carbons adjacent to any ether oxygen isperfluorinated; group C consists of copolymers comprising >10 mole % ofmonomer units derived from CH₂=CFCF₃, CF₂=CHOR_(f), or a mixture thereofin combination with monomer unit derived from 1,3 perfluorodioxoleswherein Rf is a linear or branched C1 to C6 fluoroalkyl radical havingthe formula C_(n)F_(2n−C) _(n)F_(2n−y+1)H_(y) group in which_(y+1)H_(y)wherein the number of hydrogens is less than or equal to the number offluorines, no more than two adjacent carbons atoms are bonded tohydrogens, and ether oxygen can replace one or more of the carbonsproviding at least one of the carbons adjacent to any oxygen isperfluorinated, and wherein said 1,3-perfluorodioxole has the structure

wherein R_(a) and R_(b) are independently F or linear −C_(nF) _(2n+1),optionally substituted by ether oxygen, for which n=1 to
 5. group Dconsists of copolymers comprising 40 to 60 mole % of monomer unitsderived from a monomer represented by the formula

in combination with monomer units derived from vinylidene fluoride andor vinyl fluoride wherein G and Q are independently F (but not both F),H, R_(f), or -OR_(f) wherein R_(f) is a linear or branched C1 to C5fluoroalkyl radical having the formula C_(n)F_(2n−y+1)H_(y) wherein thenumber of hydrogens is less than or equal to the number of fluorines, nomore than two adjacent carbons atoms are bonded to hydrogens, and etheroxygen can replace one or more of the carbons providing that at leastone of the carbons adjacent to any ether oxygen is perfluorinated. 1a.The method of claim 1 wherein the shaped article is a pellicle film foruse in photolithography. 1b. The method of claim 1 wherein said sourceis a laser emitting 157 nm electromagnetic radiation. 1c. The method ofclaim 1 wherein said target surface comprises a photopolymer. 1d. Themethod of claim 1 wherein said shaped article is a lens and saidfluoropolymer is a coating disposed upon the surface thereof. 1e. Themethod of claim 1 wherein said fluoropolymer is a component of anadhesive composition. 1f. The method of claim 1 wherein said shapedarticle is a lens formed from said fluoropolymer. 1g. The method ofclaim 1 wherein the fluoropolymer is a copolymer ofCH₂=C(CF₃)CF₂OCH(CF₃)₂ with vinylidene fluoride. 1h. The method of claim1 wherein the fluoropolymer is a copolymer of CH₂=C(CF₃)CF₂OCF(CF₃)₂with vinylidene fluoride. 1i. The method of claim 1 wherein thefluoropolymer is a copolymer of CF₂=CHOCF₂CF₂H with vinylidene fluoride.1j. The method of claim 1 wherein the fluoropolymer is a copolymer ofCF₂=CHOCF₂CF₂H with 4,5-difluoro-2,2-bis(trifluoromethyly 1,3-dioxole.1k. The method of claim 1 wherein the fluoropolymer is a copolymer ofCF₂=CHOCF₂CF₃ with vinylidene fluoride. 1l. The method of claim 1wherein the fluoropolymer is a copolymer of CF₂=CHOCF₂CF₂CF₂CF₃ with4,5-difluoro-2,2-bis (trifluoromethyly1 ,3-dioxole. 1m. The method ofclaim 1 wherein the fluoropolymer is a homopolymer of CH₂=CFCF₃. 1n. Themethod of claim 1 wherein the fluoropolymer is a copolymer of CH₂=CFCF₃with 4,5-difluoro-2,2-bis(trifluoromethyly 1,3-dioxole.
 2. An apparatuscomprising an activateable source of electromagnetic radiation in thewavelength range of 150-260 nanometers; and a shaped article comprisinga fluoropolymer exhibiting an absorbance/micron ≦1 at wavelengths from150 to 260 nm and a heat of fusion of <1 J/g said fluoropolymer being ahomopolymer selected from group A or copolymers from groups B, C, and Dwherein group A consists of the homopolymer of CH₂=CFCF₃ group Bconsists of copolymers comprising >25 mole % of monomer units derivedfrom CF₂=CHORf in combination with monomer units derived from vinylidenefluoride wherein R_(f) is a linear or branched Cl to C6 fluoroalkylradical having the formula C_(n)F_(2n−y+1)H_(y) wherein the number ofhydrogens is less than or equal to the number of fluorines, no more thantwo adjacent carbons atoms are bonded to hydrogens, and ether oxygen canreplace one or more of the carbons providing at least one of the carbonsadjacent to any ether oxygen is perfluorinated; group C consists ofcopolymers comprising >10 mole % of monomer units derived fromCH₂=CFCF₃, CF₂=CHOR_(f), or a mixture thereof in combination withmonomer unit derived from 1,3 perfluorodioxoles wherein R_(f) is alinear or branched C1 to C6 fluoroalkyl radical having the formulaC_(n)F_(2n−C) _(n)F_(2n−y+1)H_(y) wherein the number of hydrogens isless than or equal to the number of fluorines, no more than two adjacentcarbons atoms are bonded to hydrogens, and ether oxygen can replace oneor more of the carbons providing at least one of the carbons adjacent toany oxygen is perfluorinated, and wherein said 1,3-perfluorodioxole hasthe structure

wherein R_(a) and R_(b) are independently F or linear −C_(nF) _(2n+1),optionally substituted by ether oxygen, for which n=1 to 5; group Dconsists of copolymers comprising 40 to 60 mole % of monomer unitsderived from a monomer represented by the formula

within combination with monomer units derived from vinylidene fluorideand or vinyl fluoride wherein G and Q are independently F (but not bothF), H, R_(f), or -OR_(f) wherein Rf is a linear or branched C1 to C5fluoroalkyl radical having the formula C_(n)F_(2n−y+)H_(y) wherein thenumber of hydrogens is less than or equal to the number of fluorines, nomore than two adjacent carbons atoms are bonded to hydrogens and etheroxygen can replace one or more of the carbons providing that at leastone of the carbons adjacent to any ether oxygen is perfluorinated; saidshaped article being disposed to lie within the optical path of lightemitted from said source when said source is activated. 2a. Theapparatus of claim 2 wherein said activateable light source is a laseremitting 157 nm electromagnetic radiation. 2b. The apparatus of claim 2further comprising a target surface. 2c. The apparatus of claim 2bwherein said target surface comprises a photopolymer. 2d. The apparatusof claim 2 wherein said shaped article is a lens and said fluoropolymeris a coating disposed upon the surface thereof. 2e. The apparatus ofclaim 2 wherein said fluoropolymer is a component of an adhesivecomposition. 2f. The apparatus of claim 2 wherein said shaped article isa lens formed from said fluoropolymer. 2g. The apparatus of claim 2wherein the shaped article is a pellicle film for use inphotolithography. 2h. The apparatus of claim 2 wherein the fluoropolymeris a copolymer of CH₂=C(CF₃)CF₂0CH(CF₃)₂ with vinylidene fluoride. 2i.The apparatus of claim 2 wherein the fluoropolymer is a copolymer ofCH₂=C(CF₃)CF₂0CF(CF₃)₂ with vinylidene fluoride. 2j. The apparatus ofclaim 2 wherein the fluoropolymer is a copolymer of CF₂=CHOCF₂CF₂H withvinylidene fluoride. 2k. The apparatus of claim 2 wherein thefluoropolymer is a copolymer of CF₂=CHOCF₂CF₂H with4,5-difluoro-2,2-bis(trifluoromethyl)-1 ,3-dioxole.
 21. The apparatus ofclaim 2 wherein the fluoropolymer is a copolymer of CF₂=CHOCF₂CF₃ withvinylidene fluoride. 2m. The apparatus of claim 2 wherein thefluoropolymer is a copolymer of CF₂=CHOCF₂CF₂CF₂CF₃ with4,5-difluoro-2,2-bis(trifluoromethyl) -1 ,3-dioxole. 2n. The apparatusof claim 2 wherein the fluoropolymer is a homopolymer of CH₂=CFCF₃. 2o.The apparatus of claim 2 wherein the fluoropolymer is a copolymer ofCH₂=CFCF₃ with 4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole.